Apparatus for the interruption of fuel supply in an internal combustion engine

ABSTRACT

An apparatus for interruption of fuel supply in an internal combustion engine, during non-operation of the engine, includes a battery-operated fuel supply mechanism. The fuel supply mechanism operates independently of the engine. An ignition switch is operatively arranged to separate the fuel supply mechanism from the engine. An air-quantity measuring device is disposed within the suction tube of the internal combustion engine. The measuring device is operatively arranged to close an electrical contact when in its rest position. In that position and whenever the ignition switch is also closed, a current path is completed between the battery and a relay which is biased mechanically by a spring. Whenever the relay is not energized and the ignition switch is also closed, a current circuit is completed between the battery and the fuel supply mechanism to effect delivery of the fuel to the engine.

United States Patent Stumpp 1 1 Aug. 5, 1975 54] APPARATUS FOR THE lNTERRUPTION OF 3.398.731 8/1968 .lohansson 123/179 B x 3.811.419 5/1974 Eckert et a1. 123/119R FUEL SUPPLY IN AN INTERNAL COMBUSTION ENGINE [75] Inventor: Gerhard Stumpp. Stuttgart. Germany [73] Assignee: Robert Bosch G.m.b.H.. Stuttgart.

Germany [22] Filed: Oct. 2, 1973 [21] Appl. No.: 402,901

[30] Foreign Application Priority Data Oct. 7. 1972 Germany 2249235 [52] US. Cl ..l23/198 DB; 123/139 BL 123/ l 79 A; 123/179 G [51) Int. Cl. F02b 77/08 [58] Field of Search v. 123/179 G, 179 A. 179 8. 123/179 80, 198 DB.D1G.11 139 ST. 179 L,139 A1139 BG [56] References Cited UNITED STATES PATENTS 2.370.249 2/1945 Korte et 211. 123/179 8 X 2.912.595 11/1959 Kehm et a1 123/179 B X 2,989,644 6/1961 Schultz 123/179 8 X Primary E.\'umim'rCharles J. Myhre Antwan! E.\'umirwrW. Rutledge, Jr. Almrney, Agent, or FirmEdwin E. Greigg I 57 ABSTRACT An apparatus for interruption of fuel supply in an in ternal combustion engine, during non-operation of the engine includes a battery-operated fuel supply mechanism. The fuel supply mechanism operates indepen dently of the engine. An ignition switch is operatively arranged to separate the fuel supply mechanism from the engine. An air-quantity measuring device is disposed within the suction tube of the internal combustion engine. The measuring device is operatively arranged to close an electrical contact when in its rest position. In that position and whenever the ignition switch is also closed. a current path is completed between the battery and a relay which is biased mechanically by a spring. Whenever the relay is not energized and the ignition switch is also closed, a current circuit is completed between the battery and the fuel supply mechanism to effect delivery of the fuel to the engine.

9 Claims. 3 Drawing Figures SHEET PATENTEUAUB 51915 Fig- 2 APPARATUS FOR THE INTERRUPTION OF FUEL SUPPLY IN AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION This invention relates to an apparatus for interrupting fuel supply in an internal combustion engine during non-operation of the engine. The present invention relates, more particularly, to an apparatus for the interruption of the fuel supply in an internal combustion engine during non-operation of the engine, the apparatus including a battery-operated fuel supply mechanism, which operates independently of the engine and is separable from it by an ignition switch.

Such installations are known; however, the means for indicating that the internal combustion engine is in operation used in these known installations is either the lubricant pressure of the lubricant supply system of the internal combustion engine, or the reduced pressure in the suction tube of the internal combustion engine, or the current which the generator of the internal combustion engine delivers during the operation of the engine. These operational characteristics are not suitable, as true indications, to sense the actual operating condition of the engine with high reliability. The lubricant pressure depends very heavily on the viscosity and, therefore, on the operating temperature of the internal combustion engine. The lubricant pressure also depends on the state of maintenance of the lubricant supply and pump, if one is used, as well as the degree of contamination of the system and the pump. It is possible that the lubricant pressure is low or completely absent, yet the internal combustion engine nevertheless is in operation. A generator can fail because of damage to the generator itself or to its drive mechanism and, there- -fore, its output current, acting as an indicator of engine operation, fails. The reduced pressure in the suction tube, however, is strongly dependent on the operation and on the state of maintenance of the aspiration equipment and can also fail as a true indicator of the engine operation or as a control signal producer. In all these known installations, the control signal producer (pressure, voltage) of the control medium is completely absent during the starting of the engine and also very often for a period immediately thereafter, especially under extreme operational conditions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus for effecting interruption of fuel supply in an internal combustion engine whenever the engine is stopped.

lt is a further object of the present invention to provide an apparatus for effecting interruption of fuel supply in an internal combustion engine without any disadvantageous influence on the operating conditions of the engine.

It is another object of the present invention to provide an apparatus for effecting interruption of fuel supply in an internal combustion engine which is free from any dependency on lubricant pressure.

It is an additional object of the present invention to provide an apparatus for effecting interruption of fuel supply in an internal combustion engine which is free from any dependency on electrical generator output.

It is yet a further object of the present invention to provide an apparatus for effecting interruption of fuel supply in an internal combustion engine which is free of dependency from the level of maintenance of the lubrication system, the ignition system and the aspriation equipment.

It is yet another object of the present invention to provide an apparatus for effecting interruption of fuel supply in an internal combustion engine which is simple to manufacture and can be readily attached to the engine in a simple fashion.

The foregoing objects, as well as others which are to become clear from the text which follows, are achieved in accordance with the present invention by providing an apparatus for interruption of fuel supply in an internal combustion engine, which apparatus includes a battery-operated fuel supply mechanism. An ignition switch is operatively arranged to separate the fuel supply mechanism from the engine.

An air-quantity measuring device is disposed within the suction tube of the internal combustion engine. The measuring device is movable from its rest position, in dependence on the quantity of air passing through the suction tube. The measuring device closes an electrical contact when it is in its rest position. ln the rest position and when the ignition switch is closed, a relay energizing current-supplying circuit is completed between a battery and the relay, which is mechanically biased by a spring. Whenever the relay is not energized and the ignition switch is also closed, a current circuit between the battery and the fuel supply mechanism is completed. It is a distinct advantage of the present invention that, independently of engine temperature, the relay current circuit is interrupted even by the most minor air motion within the suction tube, i.e. even during the engine starting. Whenever this air motion occurs, a pivotal motion of the measuring device results and, thus, the fuel supply mechanism is supplied with current provided that the ignition switch is also closed. An extremely accurate signal to show when the internal combustion engine is in operation is thus provided by action of the measuring device whenever the ignition switch is also closed. Since, in general, only filtered air streams into the suction tube of the engine, the measuring device and its associated parts are protected from contamination. The apparatus is therefore extremely reliable.

Because the electrical contact, which is used in an advantageous specific embodiment according to the present invention, is a contact spring extending into the suction tube, which is mounted on an insulated base, it can be connected without difficulty to an electrical contact forming a structural part of the measuring device, which in that case is preferably grounded electrically. Only very slight constructional changes need to be made in the suction mechanism of the internal com bustion engine whose fuel metering occurs with the aid of the previously described air-quantity measuring device.

In another embodiment according to the present invention, the relay has a second switch which, when the relay is actuated, holds closed a second circuit between the battery and the fuel supply mechanism provided a starting switch in this second circuit is also closed. This has the advantage that the fuel supply mechanism can be made operational and used as soon as the engine starter is operated, without the necessity of the air measuring member to have first pivoted. When the starting process has been completed and the internal combustion engine has started, an air current has established itself in the suction tube so when the air measuring device has pivoted from its rest position. the relay circuit is interrupted and the fuel supply mechansim remains in operation.

In a further embodiment according to the present invention, the relay circuit is closable only after the elapse of a given period of time, by a timer switch acting subsequent to the closing of the ignition switch. This has the advantage that the fuel supply mechanism can be used immediately after the ignition is switched on which, for example, is an advantage when the inter nal combustion engine is very hot or when the engine is cold. When the internal combustion engine is very hot, this early switch-on of the fuel supply mechanism removes gas bubbles which may possibly reside in the fuel supply line and thus guarantees a flawless start.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of a fuel injection system illustrating a first exemplary embodiment of the present invention.

FIG. 2 is a schematic circuit diagram illustrating a second exemplary embodiment of the present invention.

FIG. 3 is a schematic circuit diagram illustrating a third exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the fuel injection system shown in FIG. 1, the combustion air flows in the direction of the arrow in an upstream section of a suction tube of an internal combustion engine (not shown in detail). An air-quantity measuring device 2 is disposed in an intermediate conical section 3 of the suction tube. The combustion air further flows through a connecting hose 4 and thence through a downstream suction tube section 5 to one or several cylinders (not shown) which form part of the internal combustion engine. The air quantity measuring device 2 comprises a plate, disposed within the suction tube transverse to the air flow direction. The measuring device 2 is pivoted within the conical section 3 of the suction tube, and follows an approximately linear function of the air quantity flowing through the suction tube. For a given constant return force acting on the measuring device 2, as well as for a constant air pressure prevailing in front of the measuring device 2, the pressure prevailing between the measuring device 2 and a conventional throttle flap, shown within the downstream suction tube section 5, also remains constant.

The air-quantity measuring device 2 directly controls a fuel metering valve 7. For the transmission of the displacement motion of the measuring device 2, a lever 8 is connected to the measuring device 2. The lever 8 is rotatable about a fixed pivot 9, as nearly frictionlessly as possible. During pivotal motion of the lever 8, a protrusion 10 which extends therefrom actuates a movable valve member of the fuel metering valve 7 which valve member includes a control slide 11. The control slide 11 is acted upon, at its rear side, by a fluid under pressure which serves as the return force for the measuring member 2. The fuel supply to the fuel metering valve 7 occurs through a fuel pump 14 which supplies fuel from a fuel reservoir 16 via a fuel line and a fuel line 17 leading to the fuel metering valve 7.

In its initial portion, the measuring device 2 is positioned within the narrowest part of the conical suction tube section 3, and the lever 8, by a contact 19 which it carries, makes contact with a short contact spring 20 extending into the suction tube. The contact spring 20 passes through an electrical insulating member 21 disposed in the wall of the suction tube upstream from the measuring device 2. The measuring device 2 is held in this illustrated position, in the absence of an air stream within the suction tube and for all attitudes of a vehicle. which may carry the engine, by the force of a very weak spring 23 which acts on the lever 8 beyond the pivotal point 9. In order to ensure that the measuring device 2 moves without any appreciable losses, it is pivoted in neutral equilibrium with respect to its pivotal point; this is achieved by a counterweight 24 mounted on the lever 8 on the other side of the pivotal point 9 from the measuring device 2.

From the contact spring 20, a current conductor 26 leads to a relay 27 which contains a switch 29 urged in its closed direction by spring 28. The conductor 26 within the relay 27 leads to a magnetizing winding 30, which, when energized, opens the switch 29 through the action of a magnetizable acutating member 31. The magnetizing winding 30 is connected, at its other end, to a conductor 32 containing an ignition switch 33. The conductor 32 is connected to the positive terminal of a battery 34. Branching off from the conductor 32, between the ignition switch 33 and the relay 27, is a conductor 35 which leads to the switch 29 and thence to one electrical terminal of the fuel pump 14. A second electrical terminal of the fuel pump 14 is connected, via a conductor 36, to the negative terminal of the battery 34 or to electrical ground, the negative terminal of the battery 34 being grounded. A warmup running unit 39 of the internal combustion engine is connected in electrical parallel with the fuel pump 14 via a branch conductor 37 branching off from the switch 29, and a branch conductor 38 branching off from the conductor 36. This warm-up running unit 39 can, as shown in FIG. 1 for example, include a warm-up running control device 40 and a heating nozzle assembly 41, connected in parallel thereto, which can be switched off from the current supply by a timer switch 42.

When the air measuring device 2 is in its initial position, as shown in FIG. I, the relay current circuit is closed by the contact 19 which makes contact with the spring 20, thereby connecting the conductor 26 to electrical ground via the lever 8 and a conductor 43, which electrically connects the pivotal point 9 to electrical ground. Thus, the magnetizing winding 30 of the relay 27 is energized and the switch 29 is opened, so that the current supply to the fuel pump 14 and to the warm-up running unit 39 is interrupted, in the absence of air flow within the suction tube. When the measuring device 2 is pivoted from its rest position by air flowing within the suction tube, then the current circuit of the relay 27 is interrupted, by movement of the contact 19 away from the spring 20, and the switch 29 is closed by the force of the spring 28 so that if the ignition switch 33 is also closed, the fuel pump I4 and the warm-up running unit 39 are supplied with current from the battery 34.

FIG. 2 illustrates a second embodiment of a circuit for controlling the relay and fuel pump circuits in schematic form. The circuit elements which correspond to those in FIG. 1 are designated by the same numerals. The relay circuit includes, as in the embodiment shown in FIG. 1, a conductor 32 connected from the positive terminal of a battery 34 to an ignition switch 33. A current path formed by the conductor 32 leads, via the ignition switch 33, to a magnetizing winding 30 of a relay 27', and hence through a conductor 26 and through a switch formed by an air measuring device 2, a lever 8 and through a conductor 43 to the negative terminal of the battery 34 or to electrical ground, the negative terminal of the battery 34 being grounded. As was the case of the circuit shown in FIG. 1, a conductor 35 branches off from the circuit which includes the conductor 32, between the ignition switch 33 and the relay 27' and leads to a switch 29 of the relay 27' and hence through a conductive connection from the switch 29 to a fuel pump 14 which is further connected through a conductor 36 to the negative terminal of the battery 34. A second switch 45 is connected in parallel to the switch 29; this switch 45 is mechanically coupled to and is simultaneously switchable with the switch 29 by magentizable member 31 or by a spring 28. The switch 45 is connected to the conductor 32 between the battery 34 and the ignition switch 33 by another conductor 46 via a starter switch 47. On the other side of the switch 45 a conductor 48 leads from the switch 45 to a conductive connection and hence to the fuel pump 14 and to a warm-up running unit 39 which is connected in parallel with the fuel pump 14.

When the ignition switch 33 is closed and the air measuring device 2 is in its initial rest position, the relay current circuit 32, 33, 30, 26, 8 and 43 is closed, and current flows in this circuit from the battery 34. In that case, current flows through the magnetizing winding 30 and, therefore, the switches 29 and 45 are moved upwardly by the megnetizable member 31 and the current connection from the conductor 32, via the ignition switch 33 and the conductor 35, to the fuel pump 14 is interrupted by the switch 29. However, a connection between the conductor 32 through the conductor 46, the switch 45 and the contuctor 48 to the fuel pump 14 is made, provided that the starting switch 47 is closed.

With the aid of this particular circuit, formed by circuit elements 32, 47, 46, 45 and 48, the fuel pump 14 and the warm-up running unit 39 can be operated simultaneously upon initation of the starting process. This is possible only, however, when the ignition switch 33 is closed, i.e. whenever the relay 27' is energized.

In the circuit of FIG. 2, as well as in that of FIG. 1, it is guaranteed that when the ignition switch 33 is open, all fuel supply installations, i.e. the fuel pump 14 and the warm-up running device 39, are switched off.

FIG. 3 illustrates a further exemplary embodiment of the invention is schematic form. As shown in FIG. 3, a conductor 32 leads from the positive terminal of the battery 34 through an ignition switch 33 and a conductor 49, containing a bimetallic timing switch 50, via a conductor connection to a magnetizing winding 30 within a relay 27. From the relay 27, a conductor 26 leads through a switch formed by an air measuring device 2 and a lever 8 to a conductor 43 to the negative terminal of a battery 34 or to electrical ground, the negative terminal of the battery 34 being grounded. A conductor 35 branches off from the conductor 49 and leads to a switch 29 of the relay 27 and hence to a fuel pump 14 and/or to a warm-up running unit 39, both of which are connected, via a conductor 36, to the negative terminal of the battery 34 or to electrical ground.

A conductor 51 branches off from the conductor 35 between the ignition switch 33 and the switch 29. The conductor 51 is connected to one terminal of a heater winding 52 for the bimetallic timing switch 50, the other terminal of which is connected, via the conductor 43 to the negative terminal of the battery 34. When the internal combustion engine is to begin operation, the ignition switch 33 is closed, and furthermore, the connection from the conductor 26 to the conductor 43 through the lever 8 of the air measuring device 2 is made during standstill of the internal combustion engine. Nevertheless, the relay circuit remains interrupted by the bimetallic timing switch 50 so that the tension spring 28 ensures that the switch 29 is closed and the circuit formed by the conductor 32, the switch 33 and the conductor 35 makes a connection to the fuel pump 14 and to the warm-up running unit 39. Thus, the internal combustion engine is immediately supplied with fuel and can be started without difficulty. After the start, the relay circuit is additionally interrupted by the pivoting motion of the air measuring member 2. Immediately after closing the ignition switch 33, however, the heater winding 52 of the bimetallic timing switch 50 is supplied with current, so that after the lapse of a predetermined adjustable time period, the switch 50 is closed. If the internal combustion engine should now be stopped, and, therefore, the connection between the conductor 26 and the conductor 43 is closed by means of the lever 8 of the air measuring device 2, then the entire relay current circuit is closed, the magnetizing winding 30 is excited and the switch 29 is opened. In this case, the current supply to the fuel pump 14 and to the warm-up running unit 39 is inter rupted, as is intended.

The above-described embodiments of the present invention ensure that the fuel supply of the internal combustion engines, during their non-operation, is inter rupted reliably when the ignition is switched off. By using the very sensitively reacting air measuring member, which also and simultaneously controls the fuel metering of the internal combustion engine, the reliable effectiveness of the installation is guaranteed. Yet the apparatus according to the invention can be realized by simple means without undue negative influence on the operation of the engine. This occurs especially well by using the bridging arrangements according to FIGS. 2 and 3, features of which incidentally can also be combined with one another. Furthermore, it is advantageous that relay 27 and the relay 27' can only be energized when the measuring device 2 is in its rest position. This is advantageous for the life of the relay used. The present invention can, of course by used in many other fuel metering installations provided with movable air measuring elements.

It is to be understood that the illustrated and described embodiments of the present invention are by way of example, various other forms and embodiments are possible without departing from the spirit and scope of the invention defined by the appended claims.

That which is claimed is:

1. A fuel supply system for an internal combustion engine comprising, in combination an air suction tube, a fuel supplying means, an ignition switch, an apparatus for interruption of fuel supply including a. control means in said fuel supply means for cutting off fuel; b. electrical contact switch means;

c. a voltage source connected in series with said electrical contact switch means, said ignition switch and said control means, said electrical contact switch means. said ignition switch means and said control means for series connected to one another;

d. relay means mechanically coupled to said electrical contact switch means for opening said contact switch means when actuated, said relay means including a winding;

e. means including circuit completing contact means in series with said winding, said ignition switch and said voltage source for actuating said relay means; and

f. means positioned within said suction tube and responsive to flow of air therein for opening said circuit completing contact means whenever air flows in said suction tube to deactivate said relay means by interrupting current flow in said winding.

2. A system as defined in claim 1, including spring means, and wherein said means positioned within said suction tube is mechanically biased in a rest position by said spring means for closing said circuit completing contact means in the absence of air flow in said suction tube.

3. A system as defined in claim 1, wherein one terminal of said voltage source and said means positioned within said suction tube are electrically grounded and said circuit completing contact means comprises a contact spring extending into said suction tube through an insulating means.

4. A system as defined in claim 1, further including a starting switch and further electrical contact switch means connected in series with one another between said voltage source and said control means in said fuel supplying means, said starting switch and said further electrical contact switch means being in parallel connection with said ignition switch and said electrical contact switch means, and said relay means being mechanically coupled to said further electrical contact switch means for closing said further electrical switch means when actuated; whereby fuel may be supplied to the engine upon initiation of starting regardless of air flow conditions in the suction tube.

5. A system as defined in claim 1, including means in circuit with said relay means for delaying actuation thereof for a predetermined period of time after closing of said ignition switch.

6. A system as defined in claim I, wherein said means positioned within said suction tube comprises a plate means carried on a lever pivoted about a fixed pivoting point, and further including a counterweight arranged on said lever for providing substantial equilibrium and a spring means coupled to said lever for holding said plate in a rest position in the absence of air flow in said suction tube.

7. A system as defined in claim I, wherein said fuel supply means includes a fuel pump.

8. A system as defined in claim 1, wherein said fuel supply means includes a warm-up running unit.

9. A system as defined in claim 1, wherein said fuel supply means includes a fuel pump and a warm-up running unit. 

1. A fuel supply system for an internal combustion engine comprising, in combination an air suction tube, a fuel supplying means, an ignition switch, an apparatus for interruption of fuel supply including a. control means in said fuel supply means for cutting off fuel; b. electrical contact switch means; c. a voltage source connected in series with said electrical contact switch means, said ignition switch and said control means, said electrical contact switch means, said ignition switch means and said control means for series connected to one another; d. relay means mechanically coupled to said electrical contact switch means for opening said contact switch means when actuated, said relay means including a winding; e. means including circuit completing contact means in series with said winding, said ignition switch and said voltage source for actuating said relay means; and f. means positioned within said suction tube and responsive to flow of air therein for opening said circuit completing contact means whenever air flows in said suction tube to deactivate said relay means by interrupting current flow in said winding.
 2. A system as defined in claim 1, including spring means, and wherein said means positioned within said suction tube is mechanically biased in a rest position by said spring means for closing said circuit completing contact means in the absence of air flow in said suction tube.
 3. A system as defined in claim 1, wherein one terminal of said voltage source and said means positioned within said suction tube are electrically grounded and said circuit completing contact means comprises a contact spring extending into said suction tube through an insulating means.
 4. A system as defined in claim 1, further including a starting switch and further electrical contact switch means connected in series with one another between said voltage source and said control means in said fuel supplying means, said starting switch and said further electrical contact switch means beinG in parallel connection with said ignition switch and said electrical contact switch means, and said relay means being mechanically coupled to said further electrical contact switch means for closing said further electrical switch means when actuated; whereby fuel may be supplied to the engine upon initiation of starting regardless of air flow conditions in the suction tube.
 5. A system as defined in claim 1, including means in circuit with said relay means for delaying actuation thereof for a predetermined period of time after closing of said ignition switch.
 6. A system as defined in claim 1, wherein said means positioned within said suction tube comprises a plate means carried on a lever pivoted about a fixed pivoting point, and further including a counterweight arranged on said lever for providing substantial equilibrium and a spring means coupled to said lever for holding said plate in a rest position in the absence of air flow in said suction tube.
 7. A system as defined in claim 1, wherein said fuel supply means includes a fuel pump.
 8. A system as defined in claim 1, wherein said fuel supply means includes a warm-up running unit.
 9. A system as defined in claim 1, wherein said fuel supply means includes a fuel pump and a warm-up running unit. 